c# - 如何使用 c# 从 Microsoft Access 表中删除一行

Question

我试过这段代码:

string sql = " DELETE FROM HotelCustomers WHERE [Room Number] =" +  textBox1.Text;
OleDbConnection My_Connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source= c:\\Users\\Documents\\HotelCustomersOld.mdb");

My_Connection.Open();

OleDbCommand My_Command = new OleDbCommand(sql, My_Connection);
My_Command.ExecuteNonQuery();

Error: Data type mismatch in criteria expression, at the line: My_Command.ExecuteNonQuery();

Answer 1

使用参数化查询来避免各种错误

   string sql = " DELETE FROM HotelCustomers WHERE [Room Number] =?";
   using(OleDbConnection My_Connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source= c:\\Users\\Documents\\HotelCustomersOld.mdb"))
   {
        My_Connection.Open();
        OleDbCommand My_Command = new OleDbCommand(sql, My_Connection);
        My_Command.Parameters.Add("@p1",  textBox1.Text);
        My_Command.ExecuteNonQuery();
   }

在您的情况下，Room NUMber 字段是 Text 类型，因此您需要将值括在单引号中，但这确实是错误的。您将代码暴露给用户在文本框中编写的恶意文本。一个很简单的 funny example here